Hydraulic brake booster including a tracking valve

Abstract

A hydraulic brake booster is proposed, in which a coupling is provided between a control valve and a booster piston. The coupling engages the control valve at a slide sheath and upon the movement of the booster piston causes it to move as well, in such a manner that tracking control is provided. A pedal push rod in this manner always keeps a certain distance from the booster piston; that is, it does not touch it. However, if the auxiliary force should fail, then the pedal push rod does touch the booster piston, and its force is transmitted mechanically.

What is claimed and desired to be secured by Letters Patent of the United States is: 
     
       1. A hydraulic brake booster for motor vehicles having a housing (5), a booster chamber in said housing, a control valve (10) in said housing disposed at least generally parallel to and beside said booster chamber for monitoring a pressure connection of said booster chamber with said control valve, said booster chamber is defined by a booster piston (8) which is disposed at least generally in axial alignment with a pedal push rod to control a brake circuit fluid pressure, said control valve (10) further comprising a slide (12) and a coaxial relatively movable slide sheath (11), a one piece coupling lever (31) in said housing operatively positioned for a non-pivotable fixed connection between said booster piston (8) and said slide sheath (11) for coupling said booster piston with said slide sheath for movement of said slide sheath by said booster piston in a braking and brake-actuating direction for both a translation and a tracking control between said control valve (10) and said booster piston (8). 
     
     
       2. A hydraulic brake booster as set forth in claim 1 which includes a control arm connected at one end to said pedal push rod and in contact with said slide for moving said slide when said pedal push rod is moved. 
     
     
       3. A hydraulic brake booster as defined by claim 1, further wherein a travel limiting spring and an electric cushion are provided between said pedal push rod and said booster piston, whereby in the event of booster force failure said travel limiting spring and said elastic cushion function as a stop damper for said pedal push rod. 
     
     
       4. A hydraulic brake booster as set forth in claim 3 which includes a control arm connected at one end to said pedal push rod and in contact with said slide for moving said slide when said pedal push rod is moved.